Serpentine Belt Tensioner

This procedure covers the removal and replacement of the serpentine belt tensioner on the 2019-2024 Toyota RAV4 with the 2.5L I4 gasoline engine.

Warnings

Tools required

Parts

• Serpentine belt tensioner assembly × 1 — Use OEM specification
• Serpentine belt (if worn or damaged) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground, engage parking brake, and place wheel chocks behind rear wheels
2. Allow engine to cool completely for at least 2 hours if recently operated
3. Open hood and secure with hood prop
4. Disconnect negative battery terminal and wait 90 seconds before proceeding
5. Locate the serpentine belt routing diagram on the radiator support or underside of hood
6. Take a clear photo of the current belt routing for reference during reinstallation

Procedure

1. 1

   Remove engine cover
   Remove the plastic engine cover by pulling upward firmly on the cover to disengage the mounting grommets. Set aside in a clean area.
2. 2

   Release belt tension and remove serpentine belt
   Locate the belt tensioner on the right side of the engine. Insert a 3/8" breaker bar or serpentine belt tool into the square 3/8" drive hole on the tensioner arm. Rotate the tensioner counterclockwise to release tension. While holding tension released, slip the belt off the alternator pulley first, then slowly release the tensioner. Remove the belt from all remaining pulleys and extract from engine bay.
   ⚠Control the tensioner arm carefully when releasing. Do not allow it to snap back as this can damage the tensioner mechanism.
3. 3

   Remove right engine mount cover (if equipped)
   Some models have a plastic cover over the right engine mount area. If present, remove the mounting bolts using a 10mm socket and set the cover aside. This provides better access to the tensioner mounting bolt.
   Torque spec

   Cover Bolts16 Nm (12 lb-ft)
4. 4

   Access tensioner mounting bolt
   The tensioner mounting bolt is located behind the tensioner assembly and may require an extension and universal joint for access. Position your socket and extension through the access area between the tensioner and engine block. Verify you have the 14mm socket fully engaged on the tensioner mounting bolt head.
5. 5

   Remove tensioner mounting bolt
   Using a 14mm socket with extension, remove the tensioner mounting bolt by turning counterclockwise. The bolt threads into the engine block. Support the tensioner assembly with your free hand as you remove the bolt to prevent it from falling.
   ⚠The tensioner assembly weighs approximately 2-3 pounds and may drop when the bolt is fully removed. Keep a hand on the tensioner to control its removal.
   Torque spec

   Belt Tensioner Bolt55 Nm (41 lb-ft)
6. 6

   Remove tensioner assembly
   Once the mounting bolt is removed, carefully maneuver the tensioner assembly out of the engine bay. You may need to rotate it slightly to clear surrounding components. Inspect the tensioner pulley for rough bearing noise by spinning it by hand, and check for oil leaks around the damper mechanism.
7. 7

   Clean mounting surface
   Using a wire brush and shop towel, clean the tensioner mounting surface on the engine block. Remove any debris, old thread locker residue, or corrosion. Ensure the mounting bolt threads in the engine block are clean and free of debris.
8. 8

   Install new tensioner assembly
   Position the new tensioner assembly into place, aligning the mounting hole with the threaded hole in the engine block. Start the tensioner mounting bolt by hand, threading it in several turns to ensure proper thread engagement. The tensioner should sit flush against the engine block mounting surface.
9. 9

   Torque tensioner mounting bolt
   Using a torque wrench with 14mm socket and extension, torque the tensioner mounting bolt to 55.0 Nm (41.0 lb-ft). Apply torque in a smooth, continuous motion. Verify the tensioner assembly is seated properly and does not rotate during final tightening.
   Torque spec

   Belt Tensioner Bolt55 Nm (41 lb-ft)
10. 10

    Install serpentine belt
    Route the new or existing serpentine belt around all pulleys according to the belt routing diagram, leaving the alternator pulley for last. Ensure the belt is properly seated in all pulley grooves. Using the breaker bar in the tensioner's 3/8" drive hole, rotate the tensioner counterclockwise to create slack. Slip the belt onto the alternator pulley, then slowly release the tensioner to apply proper tension to the belt.
    ⚠Double-check that the belt is correctly seated in all pulley grooves before releasing the tensioner. An improperly routed belt can jump off or cause component damage.
11. 11

    Reinstall engine mount cover
    If the right engine mount cover was removed, reinstall it now. Position the cover and install all mounting bolts finger-tight first, then torque to 16.0 Nm (12.0 lb-ft) in a cross pattern.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)
12. 12

    Reinstall engine cover
    Align the engine cover mounting grommets with the studs on the engine. Press down firmly on all mounting points until the cover snaps fully into place.

Reassembly

1. Reconnect the negative battery terminal and tighten securely
2. Ensure all tools and parts have been removed from the engine bay
3. Verify the serpentine belt is properly seated on all pulleys by visual inspection

Verification

• Start the engine and listen for unusual noises from the belt area. A properly installed belt should run quietly
• Observe the belt operation for 30 seconds while the engine idles. The belt should track smoothly on all pulleys without slipping or jumping
• Check that all accessories (alternator, water pump, A/C compressor) are functioning normally
• Turn the engine off and perform a final visual inspection of belt alignment on all pulleys
• Rev the engine to approximately 2000 RPM briefly and verify smooth belt operation under load
• Check for proper belt tension by pressing on the belt between pulleys - there should be minimal deflection (approximately 1/4 to 1/2 inch)

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